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<div class="title">Shi-Tomasi corner detector </div>  </div>
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<div class="textblock"><p><b>Prev Tutorial:</b> <a class="el" href="../../d4/d7d/tutorial_harris_detector.html">Harris corner detector</a></p>
<p><b>Next Tutorial:</b> <a class="el" href="../../d9/dbc/tutorial_generic_corner_detector.html">Creating your own corner detector</a></p>
<table class="doxtable">
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<th align="right"></th><th align="left"></th></tr>
<tr>
<td align="right">Original author </td><td align="left">Ana Huamán </td></tr>
<tr>
<td align="right">Compatibility </td><td align="left">OpenCV &gt;= 3.0 </td></tr>
</table>
<h2>Goal </h2>
<p>In this tutorial you will learn how to:</p>
<ul>
<li>Use the function <a class="el" href="../../dd/d1a/group__imgproc__feature.html#ga1d6bb77486c8f92d79c8793ad995d541">cv::goodFeaturesToTrack</a> to detect corners using the Shi-Tomasi method (<a class="el" href="../../d0/de3/citelist.html#CITEREF_Shi94">[223]</a>).</li>
</ul>
<h2>Theory </h2>
<h2>Code </h2>
 <div class='newInnerHTML' title='cpp' style='display: none;'>C++</div><div class='toggleable_div label_cpp' style='display: none;'><p> This tutorial code's is shown lines below. You can also download it from <a href="https://github.com/opencv/opencv/tree/master/samples/cpp/tutorial_code/TrackingMotion/goodFeaturesToTrack_Demo.cpp">here</a> </p><div class="fragment"><div class="line"></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d6/d87/imgcodecs_8hpp.html">opencv2/imgcodecs.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d4/dd5/highgui_8hpp.html">opencv2/highgui.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d1/d4f/imgproc_2include_2opencv2_2imgproc_8hpp.html">opencv2/imgproc.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &lt;iostream&gt;</span></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d2/d75/namespacecv.html">cv</a>;</div><div class="line"><span class="keyword">using namespace </span>std;</div><div class="line"></div><div class="line"><a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> src, src_gray;</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> maxCorners = 23;</div><div class="line"><span class="keywordtype">int</span> maxTrackbar = 100;</div><div class="line"></div><div class="line"><a class="code" href="../../d1/dd6/classcv_1_1RNG.html">RNG</a> rng(12345);</div><div class="line"><span class="keyword">const</span> <span class="keywordtype">char</span>* source_window = <span class="stringliteral">&quot;Image&quot;</span>;</div><div class="line"></div><div class="line"><span class="keywordtype">void</span> goodFeaturesToTrack_Demo( <span class="keywordtype">int</span>, <span class="keywordtype">void</span>* );</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main( <span class="keywordtype">int</span> argc, <span class="keywordtype">char</span>** argv )</div><div class="line">{</div><div class="line">    <a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html">CommandLineParser</a> parser( argc, argv, <span class="stringliteral">&quot;{@input | pic3.png | input image}&quot;</span> );</div><div class="line">    src = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>( <a class="code" href="../../d6/dba/group__core__utils__samples.html#ga3a33b00033b46c698ff6340d95569c13">samples::findFile</a>( parser.get&lt;<a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a>&gt;( <span class="stringliteral">&quot;@input&quot;</span> ) ) );</div><div class="line">    <span class="keywordflow">if</span>( src.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#abbec3525a852e77998aba034813fded4">empty</a>() )</div><div class="line">    {</div><div class="line">        cout &lt;&lt; <span class="stringliteral">&quot;Could not open or find the image!\n&quot;</span> &lt;&lt; endl;</div><div class="line">        cout &lt;&lt; <span class="stringliteral">&quot;Usage: &quot;</span> &lt;&lt; argv[0] &lt;&lt; <span class="stringliteral">&quot; &lt;Input image&gt;&quot;</span> &lt;&lt; endl;</div><div class="line">        <span class="keywordflow">return</span> -1;</div><div class="line">    }</div><div class="line">    <a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#ga397ae87e1288a81d2363b61574eb8cab">cvtColor</a>( src, src_gray, <a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#gga4e0972be5de079fed4e3a10e24ef5ef0a353a4b8db9040165db4dacb5bcefb6ea">COLOR_BGR2GRAY</a> );</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">namedWindow</a>( source_window );</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#gaf78d2155d30b728fc413803745b67a9b">createTrackbar</a>( <span class="stringliteral">&quot;Max corners:&quot;</span>, source_window, &amp;maxCorners, maxTrackbar, goodFeaturesToTrack_Demo );</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>( source_window, src );</div><div class="line"></div><div class="line">    goodFeaturesToTrack_Demo( 0, 0 );</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">waitKey</a>();</div><div class="line">    <span class="keywordflow">return</span> 0;</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keywordtype">void</span> goodFeaturesToTrack_Demo( <span class="keywordtype">int</span>, <span class="keywordtype">void</span>* )</div><div class="line">{</div><div class="line">    maxCorners = <a class="code" href="../../db/de0/group__core__utils.html#gafa99ec4acc4ecb2dc3c2d05da15d0e3f">MAX</a>(maxCorners, 1);</div><div class="line">    vector&lt;Point2f&gt; corners;</div><div class="line">    <span class="keywordtype">double</span> qualityLevel = 0.01;</div><div class="line">    <span class="keywordtype">double</span> minDistance = 10;</div><div class="line">    <span class="keywordtype">int</span> blockSize = 3, gradientSize = 3;</div><div class="line">    <span class="keywordtype">bool</span> useHarrisDetector = <span class="keyword">false</span>;</div><div class="line">    <span class="keywordtype">double</span> k = 0.04;</div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> copy = src.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#adff2ea98da45eae0833e73582dd4a660">clone</a>();</div><div class="line"></div><div class="line">    <a class="code" href="../../dd/d1a/group__imgproc__feature.html#ga1d6bb77486c8f92d79c8793ad995d541">goodFeaturesToTrack</a>( src_gray,</div><div class="line">                         corners,</div><div class="line">                         maxCorners,</div><div class="line">                         qualityLevel,</div><div class="line">                         minDistance,</div><div class="line">                         <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a>(),</div><div class="line">                         blockSize,</div><div class="line">                         gradientSize,</div><div class="line">                         useHarrisDetector,</div><div class="line">                         k );</div><div class="line"></div><div class="line"></div><div class="line">    cout &lt;&lt; <span class="stringliteral">&quot;** Number of corners detected: &quot;</span> &lt;&lt; corners.size() &lt;&lt; endl;</div><div class="line">    <span class="keywordtype">int</span> radius = 4;</div><div class="line">    <span class="keywordflow">for</span>( <span class="keywordtype">size_t</span> i = 0; i &lt; corners.size(); i++ )</div><div class="line">    {</div><div class="line">        <a class="code" href="../../d6/d6e/group__imgproc__draw.html#gaf10604b069374903dbd0f0488cb43670">circle</a>( copy, corners[i], radius, <a class="code" href="../../dc/d84/group__core__basic.html#ga599fe92e910c027be274233eccad7beb">Scalar</a>(rng.uniform(0,255), rng.uniform(0, 256), rng.uniform(0, 256)), <a class="code" href="../../d6/d6e/group__imgproc__draw.html#ggaf076ef45de481ac96e0ab3dc2c29a777a89c5f6beef080e6df347167f85e07b9e">FILLED</a> );</div><div class="line">    }</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">namedWindow</a>( source_window );</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>( source_window, copy );</div><div class="line">}</div></div><!-- fragment -->  </div>  <div class='newInnerHTML' title='java' style='display: none;'>Java</div><div class='toggleable_div label_java' style='display: none;'><p> This tutorial code's is shown lines below. You can also download it from <a href="https://github.com/opencv/opencv/tree/master/samples/java/tutorial_code/TrackingMotion/good_features_to_track/GoodFeaturesToTrackDemo.java">here</a> </p><div class="fragment"><div class="line"><span class="keyword">import</span> java.awt.BorderLayout;</div><div class="line"><span class="keyword">import</span> java.awt.Container;</div><div class="line"><span class="keyword">import</span> java.awt.Image;</div><div class="line"><span class="keyword">import</span> java.util.Random;</div><div class="line"></div><div class="line"><span class="keyword">import</span> javax.swing.BoxLayout;</div><div class="line"><span class="keyword">import</span> javax.swing.ImageIcon;</div><div class="line"><span class="keyword">import</span> javax.swing.JFrame;</div><div class="line"><span class="keyword">import</span> javax.swing.JLabel;</div><div class="line"><span class="keyword">import</span> javax.swing.JPanel;</div><div class="line"><span class="keyword">import</span> javax.swing.JSlider;</div><div class="line"><span class="keyword">import</span> javax.swing.event.ChangeEvent;</div><div class="line"><span class="keyword">import</span> javax.swing.event.ChangeListener;</div><div class="line"></div><div class="line"><span class="keyword">import</span> org.opencv.core.Core;</div><div class="line"><span class="keyword">import</span> org.opencv.core.Mat;</div><div class="line"><span class="keyword">import</span> org.opencv.core.MatOfPoint;</div><div class="line"><span class="keyword">import</span> org.opencv.core.Point;</div><div class="line"><span class="keyword">import</span> org.opencv.core.Scalar;</div><div class="line"><span class="keyword">import</span> org.opencv.highgui.HighGui;</div><div class="line"><span class="keyword">import</span> org.opencv.imgcodecs.Imgcodecs;</div><div class="line"><span class="keyword">import</span> org.opencv.imgproc.Imgproc;</div><div class="line"></div><div class="line"><span class="keyword">class </span>GoodFeaturesToTrack {</div><div class="line">    <span class="keyword">private</span> Mat src = <span class="keyword">new</span> Mat();</div><div class="line">    <span class="keyword">private</span> Mat srcGray = <span class="keyword">new</span> Mat();</div><div class="line">    <span class="keyword">private</span> JFrame frame;</div><div class="line">    <span class="keyword">private</span> JLabel imgLabel;</div><div class="line">    <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> <span class="keywordtype">int</span> MAX_THRESHOLD = 100;</div><div class="line">    <span class="keyword">private</span> <span class="keywordtype">int</span> maxCorners = 23;</div><div class="line">    <span class="keyword">private</span> Random rng = <span class="keyword">new</span> Random(12345);</div><div class="line"></div><div class="line">    <span class="keyword">public</span> GoodFeaturesToTrack(<a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a>[] args) {</div><div class="line">        <a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a> filename = args.length &gt; 0 ? args[0] : <span class="stringliteral">&quot;../data/pic3.png&quot;</span>;</div><div class="line">        src = Imgcodecs.imread(filename);</div><div class="line">        <span class="keywordflow">if</span> (src.empty()) {</div><div class="line">            System.err.println(<span class="stringliteral">&quot;Cannot read image: &quot;</span> + filename);</div><div class="line">            System.exit(0);</div><div class="line">        }</div><div class="line"></div><div class="line">        Imgproc.cvtColor(src, srcGray, Imgproc.COLOR_BGR2GRAY);</div><div class="line"></div><div class="line">        <span class="comment">// Create and set up the window.</span></div><div class="line">        frame = <span class="keyword">new</span> JFrame(<span class="stringliteral">&quot;Shi-Tomasi corner detector demo&quot;</span>);</div><div class="line">        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);</div><div class="line">        <span class="comment">// Set up the content pane.</span></div><div class="line">        Image img = HighGui.toBufferedImage(src);</div><div class="line">        addComponentsToPane(frame.getContentPane(), img);</div><div class="line">        <span class="comment">// Use the content pane&#39;s default BorderLayout. No need for</span></div><div class="line">        <span class="comment">// setLayout(new BorderLayout());</span></div><div class="line">        <span class="comment">// Display the window.</span></div><div class="line">        frame.pack();</div><div class="line">        frame.setVisible(<span class="keyword">true</span>);</div><div class="line">        update();</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keyword">private</span> <span class="keywordtype">void</span> addComponentsToPane(Container pane, Image img) {</div><div class="line">        <span class="keywordflow">if</span> (!(pane.getLayout() instanceof BorderLayout)) {</div><div class="line">            pane.add(<span class="keyword">new</span> JLabel(<span class="stringliteral">&quot;Container doesn&#39;t use BorderLayout!&quot;</span>));</div><div class="line">            <span class="keywordflow">return</span>;</div><div class="line">        }</div><div class="line"></div><div class="line">        JPanel sliderPanel = <span class="keyword">new</span> JPanel();</div><div class="line">        sliderPanel.setLayout(<span class="keyword">new</span> BoxLayout(sliderPanel, BoxLayout.PAGE_AXIS));</div><div class="line"></div><div class="line">        sliderPanel.add(<span class="keyword">new</span> JLabel(<span class="stringliteral">&quot;Max  corners:&quot;</span>));</div><div class="line">        JSlider slider = <span class="keyword">new</span> JSlider(0, MAX_THRESHOLD, maxCorners);</div><div class="line">        slider.setMajorTickSpacing(20);</div><div class="line">        slider.setMinorTickSpacing(10);</div><div class="line">        slider.setPaintTicks(<span class="keyword">true</span>);</div><div class="line">        slider.setPaintLabels(<span class="keyword">true</span>);</div><div class="line">        slider.addChangeListener(<span class="keyword">new</span> ChangeListener() {</div><div class="line">            @Override</div><div class="line">            <span class="keyword">public</span> <span class="keywordtype">void</span> stateChanged(ChangeEvent e) {</div><div class="line">                JSlider source = (JSlider) e.getSource();</div><div class="line">                maxCorners = source.getValue();</div><div class="line">                update();</div><div class="line">            }</div><div class="line">        });</div><div class="line">        sliderPanel.add(slider);</div><div class="line">        pane.add(sliderPanel, BorderLayout.PAGE_START);</div><div class="line"></div><div class="line">        imgLabel = <span class="keyword">new</span> JLabel(<span class="keyword">new</span> ImageIcon(img));</div><div class="line">        pane.add(imgLabel, BorderLayout.CENTER);</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keyword">private</span> <span class="keywordtype">void</span> update() {</div><div class="line">        maxCorners = Math.max(maxCorners, 1);</div><div class="line">        MatOfPoint corners = <span class="keyword">new</span> MatOfPoint();</div><div class="line">        <span class="keywordtype">double</span> qualityLevel = 0.01;</div><div class="line">        <span class="keywordtype">double</span> minDistance = 10;</div><div class="line">        <span class="keywordtype">int</span> blockSize = 3, gradientSize = 3;</div><div class="line">        <span class="keywordtype">boolean</span> useHarrisDetector = <span class="keyword">false</span>;</div><div class="line">        <span class="keywordtype">double</span> k = 0.04;</div><div class="line"></div><div class="line">        Mat copy = src.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#adff2ea98da45eae0833e73582dd4a660">clone</a>();</div><div class="line"></div><div class="line">        Imgproc.goodFeaturesToTrack(srcGray, corners, maxCorners, qualityLevel, minDistance, <span class="keyword">new</span> Mat(),</div><div class="line">                blockSize, gradientSize, useHarrisDetector, k);</div><div class="line"></div><div class="line">        System.out.println(<span class="stringliteral">&quot;** Number of corners detected: &quot;</span> + corners.rows());</div><div class="line">        <span class="keywordtype">int</span>[] cornersData = <span class="keyword">new</span> <span class="keywordtype">int</span>[(int) (corners.total() * corners.channels())];</div><div class="line">        corners.get(0, 0, cornersData);</div><div class="line">        <span class="keywordtype">int</span> radius = 4;</div><div class="line">        <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i &lt; corners.rows(); i++) {</div><div class="line">            Imgproc.circle(copy, <span class="keyword">new</span> <a class="code" href="../../dc/d84/group__core__basic.html#ga1e83eafb2d26b3c93f09e8338bcab192">Point</a>(cornersData[i * 2], cornersData[i * 2 + 1]), radius,</div><div class="line">                    <span class="keyword">new</span> <a class="code" href="../../dc/d84/group__core__basic.html#ga599fe92e910c027be274233eccad7beb">Scalar</a>(rng.nextInt(256), rng.nextInt(256), rng.nextInt(256)), Imgproc.FILLED);</div><div class="line">        }</div><div class="line"></div><div class="line">        imgLabel.setIcon(<span class="keyword">new</span> ImageIcon(HighGui.toBufferedImage(copy)));</div><div class="line">        frame.repaint();</div><div class="line">    }</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keyword">public</span> <span class="keyword">class </span>GoodFeaturesToTrackDemo {</div><div class="line">    <span class="keyword">public</span> <span class="keyword">static</span> <span class="keywordtype">void</span> main(<a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a>[] args) {</div><div class="line">        <span class="comment">// Load the native OpenCV library</span></div><div class="line">        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);</div><div class="line"></div><div class="line">        <span class="comment">// Schedule a job for the event dispatch thread:</span></div><div class="line">        <span class="comment">// creating and showing this application&#39;s GUI.</span></div><div class="line">        javax.swing.SwingUtilities.invokeLater(<span class="keyword">new</span> Runnable() {</div><div class="line">            @Override</div><div class="line">            <span class="keyword">public</span> <span class="keywordtype">void</span> run() {</div><div class="line">                <span class="keyword">new</span> GoodFeaturesToTrack(args);</div><div class="line">            }</div><div class="line">        });</div><div class="line">    }</div><div class="line">}</div></div><!-- fragment -->  </div>  <div class='newInnerHTML' title='python' style='display: none;'>Python</div><div class='toggleable_div label_python' style='display: none;'><p> This tutorial code's is shown lines below. You can also download it from <a href="https://github.com/opencv/opencv/tree/master/samples/python/tutorial_code/TrackingMotion/good_features_to_track/goodFeaturesToTrack_Demo.py">here</a> </p><div class="fragment"><div class="line"><span class="keyword">from</span> __future__ <span class="keyword">import</span> print_function</div><div class="line"><span class="keyword">import</span> cv2 <span class="keyword">as</span> cv</div><div class="line"><span class="keyword">import</span> numpy <span class="keyword">as</span> np</div><div class="line"><span class="keyword">import</span> argparse</div><div class="line"><span class="keyword">import</span> random <span class="keyword">as</span> rng</div><div class="line"></div><div class="line">source_window = <span class="stringliteral">&#39;Image&#39;</span></div><div class="line">maxTrackbar = 100</div><div class="line">rng.seed(12345)</div><div class="line"></div><div class="line"><span class="keyword">def </span>goodFeaturesToTrack_Demo(val):</div><div class="line">    maxCorners = <a class="code" href="../../d1/d10/classcv_1_1MatExpr.html#a6dff8b6e9105b6d817b493e7be157c90">max</a>(val, 1)</div><div class="line"></div><div class="line">    <span class="comment"># Parameters for Shi-Tomasi algorithm</span></div><div class="line">    qualityLevel = 0.01</div><div class="line">    minDistance = 10</div><div class="line">    blockSize = 3</div><div class="line">    gradientSize = 3</div><div class="line">    useHarrisDetector = <span class="keyword">False</span></div><div class="line">    k = 0.04</div><div class="line"></div><div class="line">    <span class="comment"># Copy the source image</span></div><div class="line">    copy = np.copy(src)</div><div class="line"></div><div class="line">    <span class="comment"># Apply corner detection</span></div><div class="line">    corners = <a class="code" href="../../dd/d1a/group__imgproc__feature.html#gac52aa0fc91b1fd4a5f5a8c7d80e04bd4">cv.goodFeaturesToTrack</a>(src_gray, maxCorners, qualityLevel, minDistance, <span class="keywordtype">None</span>, \</div><div class="line">        blockSize=blockSize, gradientSize=gradientSize, useHarrisDetector=useHarrisDetector, k=k)</div><div class="line"></div><div class="line">    <span class="comment"># Draw corners detected</span></div><div class="line">    <a class="code" href="../../df/d57/namespacecv_1_1dnn.html#a701210a0203f2786cbfd04b2bd56da47">print</a>(<span class="stringliteral">&#39;** Number of corners detected:&#39;</span>, corners.shape[0])</div><div class="line">    radius = 4</div><div class="line">    <span class="keywordflow">for</span> i <span class="keywordflow">in</span> range(corners.shape[0]):</div><div class="line">        <a class="code" href="../../d6/d6e/group__imgproc__draw.html#gaf10604b069374903dbd0f0488cb43670">cv.circle</a>(copy, (int(corners[i,0,0]), int(corners[i,0,1])), radius, (rng.randint(0,256), rng.randint(0,256), rng.randint(0,256)), cv.FILLED)</div><div class="line"></div><div class="line">    <span class="comment"># Show what you got</span></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv.namedWindow</a>(source_window)</div><div class="line">    <a class="code" href="../../df/d24/group__highgui__opengl.html#gaae7e90aa3415c68dba22a5ff2cefc25d">cv.imshow</a>(source_window, copy)</div><div class="line"></div><div class="line"><span class="comment"># Load source image and convert it to gray</span></div><div class="line">parser = argparse.ArgumentParser(description=<span class="stringliteral">&#39;Code for Shi-Tomasi corner detector tutorial.&#39;</span>)</div><div class="line">parser.add_argument(<span class="stringliteral">&#39;--input&#39;</span>, help=<span class="stringliteral">&#39;Path to input image.&#39;</span>, default=<span class="stringliteral">&#39;pic3.png&#39;</span>)</div><div class="line">args = parser.parse_args()</div><div class="line"></div><div class="line">src = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">cv.imread</a>(<a class="code" href="../../d6/dba/group__core__utils__samples.html#ga3a33b00033b46c698ff6340d95569c13">cv.samples.findFile</a>(args.input))</div><div class="line"><span class="keywordflow">if</span> src <span class="keywordflow">is</span> <span class="keywordtype">None</span>:</div><div class="line">    <a class="code" href="../../df/d57/namespacecv_1_1dnn.html#a701210a0203f2786cbfd04b2bd56da47">print</a>(<span class="stringliteral">&#39;Could not open or find the image:&#39;</span>, args.input)</div><div class="line">    exit(0)</div><div class="line"></div><div class="line">src_gray = <a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#ga397ae87e1288a81d2363b61574eb8cab">cv.cvtColor</a>(src, cv.COLOR_BGR2GRAY)</div><div class="line"></div><div class="line"><span class="comment"># Create a window and a trackbar</span></div><div class="line"><a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv.namedWindow</a>(source_window)</div><div class="line">maxCorners = 23 <span class="comment"># initial threshold</span></div><div class="line"><a class="code" href="../../d7/dfc/group__highgui.html#gaf78d2155d30b728fc413803745b67a9b">cv.createTrackbar</a>(<span class="stringliteral">&#39;Threshold: &#39;</span>, source_window, maxCorners, maxTrackbar, goodFeaturesToTrack_Demo)</div><div class="line"><a class="code" href="../../df/d24/group__highgui__opengl.html#gaae7e90aa3415c68dba22a5ff2cefc25d">cv.imshow</a>(source_window, src)</div><div class="line">goodFeaturesToTrack_Demo(maxCorners)</div><div class="line"></div><div class="line"><a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">cv.waitKey</a>()</div></div><!-- fragment -->  </div> <h2>Explanation </h2>
<h2>Result </h2>
<div class="image">
<img src="../../good_features_to_track_Shi_Tomasi.jpg" alt="good_features_to_track_Shi_Tomasi.jpg"/>
</div>
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